35.1 General characteristics
35.2 Prenatal period
35.3 Sexual maturity in men
35.4 Sexual maturity in women
35.5 Sexual motivation and behavior
35.6 Coitus, its phases and mechanisms
Profile materials Control questions Situational tasks
35.1. General characteristics
The reproductive system is a complex functional system that provides for childbirth, procreation and the future of the species. It consists of a number of functional sub-systems: sexual motivation and sexual behavior, sexual intercourse, pregnancy, development of the embryo and fetus, breastfeeding, and parenting. The beginning of its functioning is associated with puberty (in boys from 13-16 years old, in girls - from 12-15 years old); however, the anlage and formation of the system begins from the first days of the development of the organism. Thus, the functional reproduction system is the latest of the biologically functional systems at the beginning of its operation, but the first in the anlage and to start its formation, as well as the first to decline. The criterion of puberty is emergence of secondary sex characters (sex characters of the skeleton, muscles, fat distribution, body hair growth, development of mammary glands, establishment of the ovarian-menstrual cycle in women, erection and ejaculation in men, psychologi-
cal and physiological personality traits, etc.). The main critical periods of this functional system are the prenatal period, periods of puberty, and old age.
35.2. Prenatal period
In the prenatal period, genetic, gonadal, hormonal sex is established, internal and external genital organs are formed, the hypothalamus undergoes sexual differentiation.
Genetic sex is determined by the set of sex chromosomes in the fertilized oocyte cell: 46 (XX) in the female and 46 (XY) in the male body. Unfertilized germ cells have a haploid set: in sperm 23 (Y) or 23 (X), oocytes 23 (X). Genital cells, unlike somatic ones, have lower genome variability and they are used only to create a new organism. The reproductive and somatic genotypes are divided by the Weismann barrier, which prevents inheritance of acquired traits.